[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: about those claws

Makes sense to me, but then...

> From: Kevin James Dracon <jconrad@lib.drury.edu>
> To: dinosaur@usc.edu
> Cc: dinosaur@usc.edu
> Subject: about those claws
> Date: Thursday, October 02, 1997 8:14 PM
> Hello all,
> I hesitated in bringing this up (novice that I am) in hopes that an
> would mention it.  Oh well.
> Birds have a special adaptation in their feet that allows them to perch.
> The tendons which control the toes run up the leg and are rather
> unelastic.  As long as the bird keeps its leg extended, the toes can move
> freely.  If the bird bends its leg, the toes flex because the distance
> between the origin of the tendon and the toes lengthens. This allows
> perching birds to sleep while perching.  Suppose the dromaeosaurids'
> second claw worked in this manner.  When the animal ran and pulled one
> up, the second toe would flex and the claw would be pulled downward
> (someone mentioned that a dromie might disembowel itself if it kept its
> toe in the vertical position while running, made me think of this).
> When the leg straightened to contact the ground, the toe could be
> raised to the vertical position again to help prevent wear on the
> ground.  Also,if the dromaeosaurid attacked something, it might leap and
> extend its legs in the air (allowing the claw to assume the "retracted"
> position), then when it struck the animal, the impact would bend the leg
> and for the claw downward and into the prey.  With its initial momentum
> gone, the dromie would begin to slide down the side of the prey animal,
> dragging the claws (this would work better with the "all toes in the
> theory). This assumes, of course, that the dromie was hanging on and/or
> attacking with its mouth and hands.  
> Well, that's my two neurons' worth.  I expect the flames to start any
> time.  Have a wonderful evening.
> Jack